What are the risks of dust and sand on Mars?

All equipment that will be sent to Mars must be built specifically to withstand the conditions there. The environment of Mars contains dust that is much finer than that found on Earth. While the exact effects of this fine dust on technical hardware and equipment are not fully known, it is not impossible to engineer equipment that can handle the dust. The NASA rovers Spirit and Opportunity were designed to operate for a minimum of 90 days, but have exceeded their target lifespans substantially. Spirit lasted about 1900 days. Opportunity is still driving around and investigating Mars since January 2004.

It is unknown how the fine Mars dust might affect humans, should they be exposed to it. However, the astronauts will only go outside in their fully-enclosed Mars suits, and inside the habitat, the air will be filtered to remove dust.

Storms

Mars has a very thin atmosphere, about 1% of Earth’s atmosphere. Because of this, hurricane forces on Mars feel like a gentle breezes on Earth. The problem of a storm is not that it will push you over or destroy material, the problem is that Mars is extremely 'dusty'.

Dust storms

Mars has dust storms that can cover the entire planet for a whole month. This does not happen often, but smaller dust storms are quite common.
During dust storms the power output of the solar panels will decrease. While direct lighting to the panels is reduced significantly, there is still sufficient lighting from indirect light to power the crucial life support systems of the settlement. Water and oxygen production will be turned off and instead stored water and oxygen will be consumed. Lighting to the greenhouse will be lowered and other non-essential systems will be turned off.

Power during a dust storm

Mars One has designed the Mars mission to fully exploit, wherever possible, solar power generation. The mission design makes use of ‘thin film’ solar panels, which are extremely light and can be easily transported.

Solar power however has a few disadvantages: during night time, the energy must come from batteries; and during dust storms, the solar panels will yield less energy.

The solar panel system used by Mars One will deliver enough energy to power all critical systems during a dust storm.

Non-critical systems however will be shut down or restricted, to save energy:

Oxygen and water will come primarily from the storage tanks (not from powered extraction)

Dirty water will be stored (for later recycling, when full power is available)

Oxygen from the storage tanks will be consumed

Greenhouse lighting will be dimmed

EVAs will be limited to emergency repairs

Rover operation will be limited

The astronauts will have enough water stored for 15 days of normal water usage, and for 150 days if usage is limited. The oxygen storage tanks will contain enough oxygen for 60 days. Because electrical power is so critical for the survival of the crew, extra safety margins will be built into the power usage profiles for dust storms.

When required, rovers can be used to remove dust from the solar panels.

Other methods of power generation that could potentially be used on Mars are not yet available as existing technology. The most commonly referred to alternative is nuclear power. While nuclear power is a commonly used technology on Earth, a nuclear power generator in the size that would be needed for a human settlement on Mars doesn't exist yet.